Stratobus: A Feature Hybrid of Unmanned Air Vehicles for the European Air Defence Structure

Stratobus: A Feature Hybrid of Unmanned Air Vehicles for the European Air Defence Structure

5 February 2020

On January 8, 2020, France’s quest to strengthen its armed forces’ high altitude surveillance platforms entered an immature stage when Thales Alenia Space signed a contract with Direction Generale de l’ Armement (DGA) to design the Stratobus airship. The project sets out to develop an autonomous unmanned hybrid between a drone and a satellite that is capable of operating in the stratosphere (Thales Alenia Space, 2020). The contract also mandates a flight demonstration to test the aircraft’s performance in real-life environments. According to the latest reports and statements by Stratobus Product Line Manager Jean-Philippe Chessel, the first demonstration is planned for the end of 2023 (Thales Alenia Space, 2020).


The 108-feet balloon will be powered solely by solar energy, while four electric motors will be working daily. After a year in the stratosphere, the Stratobus would return to the ground for maintenance, after which another balloon would be launched to continue the program. Given the demands for innovative solutions to tackle the evolving sets of problems from border control to counter-terrorism, Thales representatives highlighted that the Stratobus could conduct a variety of satellite- and drone-like missions because of its hybrid design. First, the airship has been designed with features optimised for remote sensing while improving the quality of telecommunications. Second, it is highly suited for environmental monitoring missions (Henry, 2020; Thales Alenia Space, 2020).

Not a New Idea

The use of aerostats or “lighter than air” aircraft for military purposes has been around since the invention of the hot air balloon by the brothers Mongolfier. This is no different today, with the development of the Stratobus that fits into a series of 21st-century technological developments to conquer the stratosphere as an alternative area of operations for satellites.

The military applications of Aerostats and airships have seen the light for example, through the US Army’s Rapid Aerostat Initial Development (RAPID) program and the Joint Land Attack Cruise Missile Defense Elevated Netted Sensor (JLENS) System. These initiatives, with the main contractors being Raytheon and TCOM, emerged from the urgent need of aerostats with surveillance capabilities in Iraq and Afghanistan, which led to various upgrades in the use of blimps for military purposes. These airships, equipped with radar systems, are used for surveillance, threat detection, and tracking of airborne objects like cruise missiles or enemy aircraft and surface moving objects like trains, boats, and cars (Magnuson, 2015). The primary innovative use for aerostats has mainly been their capacity to carry heavy surveillance equipment within high altitude and staying in a fixed location for an extended period while maintaining a relatively cheap price tag (Wolf, 2013). These vessels have to remain connected to the ground to maintain their geostationary location, to keep a constant supply of power and to transfer the collected data to the ground, which is limiting the operational capabilities of the blimp. 


To overcome these restrictions, companies have been looking to other possible high altitude platforms as a more efficient surveillance capacity. The remote-controlled HAV 304 (renamed Airlander 10 after civilian commercialization), or Lockheed Martins’ High-Altitude Airship (HAA) are good examples of blimps developed for operating actions (Magnuson, 2015). With these kinds of heavy lifters, the main problem lies with the longevity of the mission and structural constraints. Although these airships can sustain missions for several weeks, it will always have to land to refuel, making its deployment more time consuming and costly. The HAV 304 project was thus terminated by the US Army, as there were numerous technical and performance challenges in the required time-frame, which led to constrained resources (Szondy, 2013).

To tackle the challenges of refueling, companies have been looking at the possibility of solar-powered aircraft. Airbus recently completed the development of its Zephyr S, which flew for 25 days during its maiden flight in 2018 and carried prototypes of Earth observation payloads. (Kucinski, 2018). This is the first UAV to have made it to the stratosphere. Besides Airbus, other major companies and government agencies have been trying to develop their stratospheric drones, mostly in close cooperation with military entities. These include the Aquila aircraft (Facebook), HAWK 30 drone (SoftBank), Pathfinder and Helios (NASA), and Phantom Eye (Boeing). However, the major obstacle in developing these UAVs is the delicate structure of the aircraft, which needs to be light and large in order to be efficient. This makes it very fragile and heavily limits the payload (Cherney, 2019).

Another surveillance challenge with these kinds of drones is that they are dynamic, and even though they can be in operation for extended periods, it is challenging to keep observing fixed geospatial location. This is where the potential for stratospheric airships like the Stratobus comes in. They have the advantage of remaining aerostatic, while their solar-powered system eliminates the need to refuel. Plus, their sturdy structure gives them the potential to carry heavier payloads. (European Space Defence Agency, 2018)

Seen the previous developments, the constant challenges and failures in other companies and the potentially high yields of HAPS, the European Space Agency (ESA) has developed multidisciplinary studies to understand the potentials and possible pitfalls of such projects. These concluded that because of the potentially high commercial value, there is a strong possibility of developing the needed technological capabilities for the launch of operational platforms by 2025 (European Space Defence Agency, 2018).

European Defense, Security and Interoperability

Jean-Philippe Chessel, Director of the Stratobus project, has underlined that the Stratobus project could benefit future defence programs in the space domain by improving the maintenance of telecoms and Earth observation due to increased monitoring capacity (Thales, 2017). Moreover, he added that the European countries’ desire for further collaboration in the defence sector could be supported by the project’s potential since, despite the French initiative. Europe’s defence and security agendas require multilateral approaches, considering that the contemporary threats and problems concern all Member States. For instance, the Stratobus project offers innovative solutions in countering illicit activities from terrorism to drug trafficking. Through broader area coverage and increased regional control, the Stratobus enhances the detection of such activities which would allow European militaries to operate based on more accurate and accountable information.  


The potential for increased environmental control bolsters maritime intelligence, surveillance, and reconnaissance (ISR) capabilities that could help European forces better control the flow of migration, tackle piracy, and track down human trafficking groups. Taking into account that there are several difficulties in controlling the illegal human trafficking from the Libyan to the Aegean Sea, such innovations could promote cooperation between countries such as Greece and Italy that have been trying to control the steadily rising numbers of refugees and migrants arriving on their shores. 

Besides, the environmental vulnerabilities such as the Swedish fires in July 2018 are clear signals for stronger defence interoperability in order to mitigate the severe impacts they have on national assets and the quality of life. Sweden’s cooperation with other European countries in terms of equipment and human resources presented a necessity for interoperability against such natural disasters (European Commission, 2018).  While the EU Civil Protection Mechanism facilitated a robust response to the devastating fires during the summer of 2018, through the tangible support of various European countries, such as Italy, France, Germany, Lithuania, Denmark, Portugal and Poland, its efficiency and its interoperability potential could be improved by the potential of the Stratobus’s wide-area coverage. Precisely, it helps strengthen the process of information collection necessary to guide fire-fighting operations that might involve more than one Member States. 

Because natural disasters might inflict extensive cross-border damages, the Stratobus could offer enormous support in terms of providing much needed geospatial information, which would allow more efficient planning of disaster relief operations. Potential collaboration with the Copernicus Emergency Management Service, which produces satellite maps for better prevention, preparedness, and response activities, is also a significant variable for the EU’s security in this domain (European Union, 2020).

Challenges to the Success of the Program

The necessity of sustainable operating dynamics will be strengthened by using an airship that is powered only with solar energy. This source of fuel is an essential component of the Stratobus project since it would help reduce emissions during monitoring missions while still providing regional security control. However, there are financial barriers that could prevent industry developers from shifting to the use of solar. Some of the Member States’ recommendations for the EU budget from 2021 to 2027 seems to question the profit of investments in defence, thereby raising significant challenges for such projects. Going into 2020, Finland proposed financial cuts in a multi-year budget of 1.134 trillion euros to 1.087 trillion euros, minimising the size of the European Defence Fund (EDF) (Euractiv, 2020). Taking into consideration the Commission’s statements for the necessity to facilitate the EU’s potential in defence cooperation (European Commission, 2018), the operational logic of Stratobus might offer a tangible solution. 

Investments in aircrafts that are designed to operate in the stratosphere rise further technological concerns, such as its reliability in energy storage and thermal management. Furthermore, an additional set of difficulties stem from the fact that the total lifespan of a  Stratobus airship is expected to last only five years. This brings up further financial concerns regarding the maintenance of the airship. Last but not least, the discourse on EU legislative barriers regarding the operational ability of Unmanned Air Vehicles (UAV) should also be on the table. The slow integration of UAVs at the European level is linked to the EU’s rigid legislation, regarding tight restrictions on flights (Sprenger, 2020). As a result, these potential legal barriers should also be considered in order to allow the Stratobus to – once it has reached initial operating capability and ready to enter into service – fully function in the framework of EU interoperability. 

Future Trajectory

The Stratobus project has the potential to modernise the EU’s common defence architecture, improving the intelligence, surveillance, and reconnaissance sectors by establishing the foundations for the integration of autonomous aircrafts. These upgrades could result in greater interoperability in European armed forces, especially in regional security fields such as counter-terrorism, border control, and cybersecurity. Moreover, the project’s potential to modernise European defence might also serve as an innovative paradigm. The attractivity of the project could incentivise the Member States to deploy UAVs in order to provide the necessary support across naval, air, ground, and even space domains. The potential success of the Stratobus could be the starting point of a new generation of stratospheric vehicles that could provide tremendous added value for European defence cooperation. 

Written by Theodoros Kaloudiotis and Eric Peers, European Defence Researchers at Finabel – European Army Interoperability Centre


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